1. Field of the Invention
The invention relates to a mechanism for manoeuvring a closing or sun protection installation. The invention also relates to a closing or sun protection installation incorporating such a mechanism.
2. Brief Description of Related Art
Closing installation is understood to mean doors, portals, blinds, shutters and equivalent equipment.
In a closing or sun protection installation, a screen, which may be a supple shade body or a rigid or semi-rigid panel, is displaced opposite an opening in order to close the latter selectively. The weight of this screen exerts on the drive means a torque which is variable, particularly as a function of the position of this screen. It is known to use so-called “compensating” springs to compensate this torque at least partially.
For an installation to function correctly, it is necessary that the effort of compensation exerted by the spring be adapted to the torque developed by the screen which influences the drive means. This torque is a function of the dimensions of the screen, of its specific weight and of its position with respect to the opening. It is therefore known to provide means for adjusting a compensating spring, particularly when it is initially loaded. U.S. Pat. No. 4,817,927 teaches mounting one end of a compensating spring on a ring capable of rotating about a fixed pin of the installation and immobilizing this ring in rotation with respect to this pin thanks to a screw which, when the tension of the spring is adjusted, must be untightened. This obliges the operator to exert, during such adjustment, a torque on the ring in order to avoid an accidental and sudden unloading of the spring. It is therefore necessary for the operator to manipulate, in one hand, a tool for exerting a torque on the ring and, in the other hand, the locking screw, this involving a particular technical gesture which is not necessarily accessible to a person of little experience.
It is also known, for example from U.S. Pat. No. 4,981,165, to use a wheel and endless screw system for adjusting the position of a ring on which the end of a compensating spring is immobilized. Such a device is relatively complex and expensive.
It is a more particular object of the invention to overcome these drawbacks by proposing a manoeuvring mechanism in which the tension of a compensating spring may be adjusted easily and in safety, by means of a simple and reliable device.